Moved taxonomy integration for web form inside CMS_TAXONOMY_API.

Moved a few helpers routine from CMS_RESPONSE to CMS_API.
Added CMS_CONTENT.identifier: detachable READABLE_STRING_32 .

modules/node/content/cms_node.e

@@ -11,8 +11,10 @@ deferred class
 
 inherit
 	CMS_CONTENT
+		rename
+			has_identifier as has_id
 		redefine
-			debug_output
+			debug_output, has_id
 		end
 
 	REFACTORING_HELPER
@@ -63,6 +65,12 @@ feature -- Conversion
 
 feature -- Access
 
+	identifier: detachable IMMUTABLE_STRING_32
+			-- Optional identifier.
+		do
+			create Result.make_from_string_general (id.out)
+		end
+
 	id: INTEGER_64 assign set_id
 			-- Unique id.
 			--| Should we use NATURAL_64 instead?